Synchronous dynamo-electric machine.



S. H. MARTIN. SYNCHRONOUS DYNAMO ELECTRIC MACHINE. APPLICATION HLED JUNE2.1913.

2 SHEETS-SHEET 1.

S. H. MARHN.

SYNCHRONOUS DYNAMO ELECTRIC NEACFHNE.

APPLICATION FILED JUNE 2.1913.

1 ,226,901 Patented May 22, 1917.

2 SHEET$SHEET 2.

SAMUEL I-I. MARTIN, OF CHICAGO, ILLINOIS.

SYNCI-IRONOUS DYNAMO-ELECTRIC MACHINE.

Application filed June 2, 1913.

To all 1072,0772 it may concern.

Be it known that I, SAMUEL H. MARTIN, a citizen of the United States ofAmerica, and. a resident of Chicago, county of Cook, and State ofIllinois, have invented certain new and useful Improvements inSynchronous Dynamo-Electric Machines, of which the following is aspecification.

This invention relates to improvements in dynamo electric machines, andmore particularly to machines of this class adapted for motor serviceand also for the conversion of single or polyphase alternating currentinto direct current and vice versa.

The main objects of this invention a re to provide an improvedconstruction and arrangement of circuits for motors of the characterdescribed, adapted to operate ethciently on single or polyphasealternating current; to provide circuit means in the machines forcontrolling the starting of machines made in accordance with thisinvention upon due setting of the current supply switch; to provide andarrange regulating windings both in the field and line circuits and alsoindependently thereof for better regulation or" speed; to provide animproved form of magnetic screen with windings oisposed thereon adaptedto most effectively distribute and control the field flux in startng andwhen operating under various conditions of load and no load, andespecially to suppress line surges and prevent hunt ing; to providesupplementary field windings of substantially the same lowself-inductance and resistance as the armature, to facilitate startingwith a considerable degree of torque and a high power factor; to providemeans for changing the circuit connections by a simple operation fromstarting to running conditions, as for switching certain field excitingcoils to operate on alternating current in starting, and to serve as anelectric damper when full speed is attained; to arrange the circuits todeliver direct current through the starting leads and switch contactswhen the machine operating normally; and to so construct a machine olthis character as to permit of its being operated either as a motor oras a rotary converter.

A specific construction embodying this invention is illustrated in theaccompanying drawings in which:

Figure 1 is a transverse central section of the machine showing therelative position Specification of Letters Patent.

Patented May 22, 191 *7.

Serial No. 771,172.

of the main poles, armature, screen, and the several windings, thearmature and brushes be ng indicated by dotted lines, and the electricalconnections being shown diagrammati- Cally.

Fig. 2 is a diagram of the circuit connections with the windings shownin their relative angular position about the center or axis of symmetry.

Fig. 3 is a longitudinal axial section through the field yoke, poles,and armature showing the relative position of the several parts.

In the construction shown in the drawings, the stationary frame of themachine is formed to include a magnetic field member, arranged in theform of a closed peripheral yoke 3, having poles r symmetricallydisposed in pairs and projecting inwardly therefrom in radial position,in combination with a closed ring member 5 rigidly embraced by the innerfaces ofthe said poles and supported thereby. The armature (5 isjournaled concentrically in the said frame to rotate within said ringwith a small air gap between the outer surface of the armature and thering.

The said ring is constructed to consist of a laminated core comprisingthin layers or sheets 9 or annealed soft iron radially disposed and heldpressed closely together between heavy rings or plates 10 disposed onopposite sides, said plates being nently clamped together by means of aplurality of heavy bolts or bars 12 adapted for setting up or rivetingto bind the parts together substantially integrally, the said laminationsheets constituting a magnetic screen element proper,- and the saidclamping plates and bars, both consisting of brass, copper, or othergood current conducting material, constituting sul'istantially asquirrel cage damper.

The said ring is provided with an inner mripheral series of transverselydisposed slots 13, svmmetricall y arranged for housing the starting andother supplementary coils to be described. By this construction the ringconstitutes substantially a slotted housing with inwardlyprojecting'teeth 1t separated by the said slots.

The said teeth are perforated trans versely of the ring to receive andhouse the said clamping bars 12 which hold the parts of the ringtogether, and to provide for dis posing the induction members of thesquirrel cage damper closely adjacent to the inner surface of the screenring, and in close proximity to the armature where their influence ismost efiicient for steadying the magnetic fiux and preventing pulsationsthereof.

In the construction shown in Fig. 1 there are twenty-four slots andtwenty-four teeth, four of the teeth 15 disposed in quadrature being inaxial alinement with the adjacent poles respectively, thus providing sixslots between each two adjacent main poles. Of these slots the middletwo are occupied by ring windings 16 connected in series with the mainfield coils 17 across the direct current brushes 18, and the adjacentslots, one on each side, are occupied each by one side of the adjacentmain field supplementary coils 19 respectively, and the two remainingslots, one on each side and adjacent to the polar axial teeth 15, areoccupied by one of the short circuited damping coils 20 which areadapted and arranged to cooperate with the said squirrel cage damper tofurther steady the magnetic flux. The disposition of the effective partsof these coils 20 di rectly opposite the main pole faces renders themespecially efiicient as supplementary damper windings.

The direct current brushes are disposed in quadrature on the commutator18.1 and alternate brushes are connected in pairs of like polarity.

The said supplementary or starting field coils 19 and damper coils 20may be and preferably are form wound coils, the former each consistingof a medium or moderate number of turns of medium sized wire and thelatter a very few turns of a large conductor; said coils all beingadapted to slip into place in their respective slots before the armatureis put in place.

The said ring wound coils 16 consist each of many turns of fine wirecorresponding with that of the main field coils 17 with which they areconnected in series.

The field exciting coils 17 and 19 are connected to supplement eachother in building 22 25 31, 19, 1a, 19, 19, is-

up main pole fluxes of alternating polarity in starting, and the ringwound coils 16 are connected to oppose leakage through the screen at alltimes and to increase the strength of the main poles. When full speed isattained the coils 19 are short circuited in series to serve as adamper.

The normal working polarity of the main poles is indicated by theletters N and S on Fig. 1. The magnetic flux induced by the ring woundcoils 16 is indicated by the arrows, associated therewith. In startingthe motor on alternating current the effect of the coils 16 is small butthe flux induced by the supplementary windings 19 largely follows thesame course and is assisted somewhat by the coils 16.

A three pole double throw line switch 21 with one contact on thestarting side omitted is connected to lead the alternating power currentthrough the supplementary field coils 19 and armature winding 22 instarting, and to switch over to lead the power current directly to thealternating current brushes 23 on the slip ring 29.1 and to shortcircuit the coils 19 when the machine has come up to speed. The saidswitch 21 comprises three central or hinge contacts 24, 25 and 26, threecontacts 27 2S and 29 on the running side indicated by R, and twocontacts 30 and 31 on the starting side indicated by S.

The switch contacts 26 and 29 connected permanently to one of the directcurrent brushes 18 and adjacently connected coil 19 on one side of thestarting field coils 19, and to the switch contact 31 and adjacentlyconnected coil 19 on the opposite side of the starting field coils 19respectively, so as to connect the said coils 19 in series with thearmature in starting and so as to short circuit them when the switch 21is thrown to its running position.

hen. the switch 21 is thrown to its startin g position, the circuit isclosed through the elements indicated by the following numera ls takenin order:

lVhen the circuit is connected thus the greater part of the current isshunted through the armature 22 rather than through the field coils 16and 17, which have relatively high ohmic resistance as well as selfinductance.

hen the switch 21 is thrown to its running position the alternatingcurrent is wlosed through the elements indicated by the followingnumerals taken in order: 25 282823.12223.1232724;; and the startingfield coils 19 are short circuited in series through the switch contacts26 and 29, thus converting them into an electrical damper which willassist the other damper elements herein referred to, to steady thefield. The direct current circuit for exciting the field is closedthrough the elements indicated by the following numerals taken in order:22181716-17 16-1716- 17161822. The main field coils 17 and screen ringcoils 16 are connected in alternate series across the direct currentbrushes in one circuit.

By the arrangement herein provided direct current is fed normally to theswitch contacts and 31 by a circuit containing the following elements inorder: 301822 18-262931; the current being delivered from the contacts30 and 31 for any purpose which may be desired, as indicated by dottedlines.

When the machine is not in use the switch 21 is open. In starting themachine to run on alternating current, the switch 21 is thrown to thestarting position, that is to the left on the drawings, then as soon asthe machine comes up to synchronism the switch is thrown over to therunning position, that is to the right on the drawings, whereby thepower current is fed directly to the slip rings, and the direct currentcircuit is so connected as to provide for the supply of direct currentfor whatever purposes are de sired, as for light and power and includingfield excitation, as best shown by Fig. 2. A switch 35 is preferablyused for delivering direct current from the machine.

As above shown, when the current is first turned on by throwing theswitch to the starting position, the armature windings are connected inshunt With the main field coils and screen ring coils. The greater partof the current, entering through the supplementary field coils 19,passes through the armature, and but little passes through the coils 16and 17 because of their high resistance and self-inductance. As thearmature and supplementary field windings are connected in series instarting the field and armature currents are in phase. Hence the machineis started substantially as a direct current series motor on alternatingcurrent, the field fiuX being generated chiefly by the supplementary orstarting coils 19. The arrangement of the coils 19 on the screen ispeculiarly advantageous for starting, as the greater part of thealternating magnetic flux induced thereby may take a short course of lowreluctance through the screen rather than out through the yoke and mainpole pieces proper. Thus in starting, the iron losses are small and arelatively strong field is immediately produced by the alternatingcurrent in the coils 19 Without much current in the main shunt fieldcoils 17 and without much flux generated in the yoke 3 and main polecores 4.

As soon as the starting switch is thrown to the running position therotating field developed in the armature reacts upon the v squirrelcage, as in an induction motor, especially in case of overload, andthereby helps to steady the action of the machine.

lVhile this invention applies to both single and polyphase machines, Ihave preferred to illustrate the same in its simplest form as applied tosingle phase machines.

This invention is an improvement over the device of my copendingapplication Serial No. 716,407, filed August 22, 1912, wherein themagnetic screen comprises a series of with windings quite different inarrangement and use from those of the prior application.

Although but one specific embodiment of this invention is herein shown,it will be understood that numerous details of the construction shownmay be altered or omitted without departing from the spirit of thisinvention, as defined by the following claims.

I claim:

1. In a. device of the class described, an annular magnetic screencomprising a laminated core, in combination with a pair of electricallyconductive annular clamping rings disposed on opposite sides of saidscreen and electrically conductive clamping bars for binding thelaminations together between said plates, the laminations and platesbeing formed with a peripheral series of alternately arranged slots andperforated teeth substantially uniformly distributed, form windingsspaced symmetrically on said screen in certain of said slots andconnected in series, ring windings disposed in certain of said slotsbetween the first mentioned windings, and closed form windings disposedin certain of said slots on opposite sides of said ring windings, andsynunetrically overlapping the first mentioned windings, said bars beinghoused in said perforated teeth.

2. I11 a device of the class described, a field system of unitarycharacter comprising a magnetic yoke, pole pieces thereon, and anannular magnetic screen having a peripheral series of closely spaced andsubstantially uniformly distributed slots and perforated teethalternately arranged, in combination with electric windings disposed insaid slots and teeth respectively.

3. In a device of the class described, a field system of unitarycharacter comprising an annular magnetic screen having a peripheralseries of uniformly spaced and trans versely disposed slots of likecharacter formed around its inner surface, in combination with a seriesof windings disposed in said slots.

4. In a device of the class described, an annular magnetic screen formedwith an inner peripheral series of alternately disposed like teeth andlike slots, in combination with damper windings and supplementarymagnetizing coils symmetrically disposed within said slots.

5. In a device of the class described, a stalit] tionary frame formedwith a peripheral yoke having inwardly projecting field poles th reon,an armature journaled concentrically within said poles, and a continuousmagnetic screen disposed between said poles and said armature with asuitable air gap for clearance of the armature, said screen being formedwith an inner peripheral series of uniformly spaced and alternatelyarranged teeth and slots, substantially as and for the purpose setforth.

6. In a device of the class described, an annular series of stationaryfield poles, an armature journaled to rotate concentrically within saidpoles, and a magnetic screen embraced rigidly by said poles andsurrounding the armature, said screen having a continuous series ofuniformly distributed transverse slots arranged around its innersurface.

7. In a device of the class described, an annular series of stationarypoles, an arma ture j ournaled to rotate concentrically with: in saidpoles, a continuous annular damper disposed between said armature andpoles, supporting means for said damper embraced rigidly by said poles,said supporting means being formed with a continuous series of uniformlyspaced inwardly projecting teeth perforated transversely and said dampercomprising substantially a pair of heavy conductor plates radiallydisposed and spaced apart transversely, and a series of transverselydisposed conductor bars rigidly mounted in the tooth perforations andconnecting said plates.

8. In a device of the class described, an annular series of stationarypoles, an armature journaled to rotate concentrically within said poles,a ring member disposed be tween said poles and said armature and rigidlyembraced by said poles, said ring member comprising a combined magneticscreen and electric damper consisting of a group of soft ironlaminations disposed transversely of the axis in a radial direction, apair of heavy conductor plates disposed on opposite sides of said groupof laminations and a continuous series of uniformly spaced heavyconductor bars transversely disposed and arranged to clamp saidlaminations tightly between said plates, and said ring being formed witha peripheral series of inwardly projecting teeth perforated transverselyof the ring for housing said bars.

9. In a device of the class described, an annular series of stationarypoles, an armature journaled to rotate concentrically within said poles,an annular magnetic screen disposed between said poles and armature andrigidly embraced by said poles, said screen being provided with asubstantially uniform annular series of slots disposed transversely onits inner side, supplementary field windings in said slots arranged tostrengthen the adjacent fields respectively, and a source of alternatingcurrent connected to energize said poles and windings with alternatingcurrent.

10. In a device of the class described, an annular series of stationarypoles, an armature ournaled to rotate concentrically within said poles,an annular magnetic screen disposed between said poles and armature andrigidly embraced by said poles, said screen being provided with a seriesof similar slots uniformly distributed and disposed transversely on itsinner side. and ring wound coils disposed in certain of said slotsadapted to oppose flux leakage through said screen.

11. In a device of the class described, an annular series ofstationarily mounted main poles uniformly distributed, an armaturehaving both direct and alternating current brushes disposed to rotatewithin said poles and a screen ring rigidly embraced by said poles anddisposed between the poles and the said armature, two sets of fieldwindings disposed on the said poles and on the screen ring centrallybetween said poles respectively and connected in series between thedirect current brushes, the latter or medial windings being ring wound.

12. In a dynamo electric machine the combination of a field frame havingan annular series of inwardly projecting poles symmetrically spacedapart, an armature journaled to rotate concentrically within said fieldpoles, a screen and damper constructed in combination as a ring disposedbetween the inwardly turned pole faces and the armature and stationarilyheld by the said poles, said ring having a series of alternatelydisposed teeth and slots on its inner side, said slots containingsupplementary windings and said teeth being perforated and provided withconductors connected in squirrel cage arrangement.

13. In a device of the class described, an annular series of stationarypoles, an armature j ournaled to rotate concentrically within saidpoles, an annular magnetic screen disposed between said poles andarmature and rigidly embraced by said poles, said screen being providedwith a continuous annular series of slots disposed transversely on itsinner side, form wound supplementary field windings disposed in certainof said slots opposite the said poles, ring wound windings disposed incertain of said slots intermediate of said poles, and form wound damperwindings arranged with opposite sides housed in certain of said slotsopposite adjacent poles.

14. In a dynamo-electric machine a field member having projecting poles,an armature with a commutator and brushes therefor, a screen disposedbetween said armature and poles and fixed to the latter, shuntmagnetizing windings for said field member connected across saidbrushes, and series supplementary magnetizing windings disposed uponsaid screen opposite said poles respectively.

15. In a dynamo electric machine, the combination of a field framehaving an annular series of inwardly projecting poles symmetricallyspaced apart and magnetizing means therefor, an armature adapted forboth direct and alternating current jour naled to rotate concentricallywithin said field poles, and a screen and dannper constructed incombination as a ring disposed between the inwardly turned pole facesand the armature and stationarily held by the said poles, said ringhaving a series 01 al ternately disposed teeth and slots on its innerside, certain of said slots containing supplementary windings disposedopposite said poles to strengthen the latter, and said teeth beingperforated and provided with conductors connected in squirrel cagearrangement.

16. A device of the class described coniprising in combination a fieldmember with apair of poles spaced apart, an armature having slip ringsand a commutator with brushes therefor respectively, a screen disposedbetween said armature and poles, a shunt winding for said field memberconnected across the direct current brushes, and series windingsdisposed on said screen 0pposite said poles respectively, and having oneside connected to one of the direct current brushes.

Signed at Chicago this 28th day ol? May, 1913.

SAMUEL H. MARTIN.

Witnesses PHILIP B. VVooDWoRTH, FRED M. DAVIS.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents Washington, D. 0.

